Answer:
2.48 g
Explanation:
From the question given above, the following data were obtained:
Original amount (N₀) = 10 g
Time (t) = 1407.6 million years
Amount remaining (N) =?
Next, we shall determine the rate of decay (K) of uranium-235. This can be obtained as follow:
NOTE: Uranium-235 has a half life of 700 million years.
Decay constant (K) =?
Half life (t½) = 700 million years
K = 0.693/t½
K = 0.693/700
K = 9.9×10¯⁴ / year
Therefore, Uranium-235 decay at a rate of 9.9×10¯⁴ / year.
Finally, we shall determine the amount of Uranium-235 remaining after 1407.6 million years as follow:
Original amount (N₀) = 10 g
Time (t) = 1407.6 million years
Decay constant (K) = 9.9×10¯⁴ / year
Amount remaining (N) =?
Log (N₀/N) = kt /2.3
Log (10/N) = (9.9×10¯⁴ × 1407.6) /2.3
Log (10/N) = 0.60588
10/N = antilog (0.60588)
10/N = 4.04
Cross multiply
10 = 4.04 × N
Divide both side by 4.04
N = 10/4.04
N = 2.48 g
Therefore, 2.48 g of uranium-235 is remaining after 1407.6 million years.
If you have a 10 gram sample of uranium-235 there would still be uranium-235 after 1407.6 million years - 2.5 grams.
The half-life of U-235 is the time it takes for half the U to decay. We know that U-235 has 703.8 million years as its half-life which means it takes 703.8 million years to half of its initial amount.
After one half-life, half (50 %) of the original amount will remain. After a second half-life, half of that amount (25 %) will remain, and so on.We can construct a table as follows:
No. of Fraction Amount
half-lives t/(yr × 10⁶) remaining remaining/g
1 703.8 ½ 10/2 = 5
2 1407.6 ¼ 10/4 = 2.50
Thus, the correct answer is - 2.5 grams.
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Please please help :(
Answer: ¹²₅C
Explanation:
¹²₅C is incorrect. The superscript is the atomic mass. This varies between each element. The subscript is the atomic number. This doesn't change. You will see every element has the correct atomic atomic number except for Carbon. Carbon should have atomic number 6.
An atom with 17 protons, 18 neutrons, and 18 electrons will have a charge of
Answer:
It's atomic mass is 35
Explanation:
The cell organelles that contains chlorophyll
Answer:
In plants, photosynthesis takes place in chloroplasts, which contain the chlorophyll. Chloroplasts are surrounded by a double membrane and contain a third inner membrane, called the thylakoid membrane, that forms long folds within the organelle.Which object has the lowest density
beach ball
water
sand
SHOW YOUR WORK!!!!!!!!!!!!!!!
An experiment performed to determine the density of lead yields a value of 10.95 g/cm3. The accepted value for the density of lead is 11.342 g/cm3. Find the percent error.
Answer:
3.45618%
Explanation:
Percent Error = measured value - accepted value/ accepted value x 100
Measured Value: 10.95
Accepted Value: 11.342
Work:
[tex]\frac{10.95-11.342}{11.342} *100[/tex]
[tex]\frac{-0.392}{11.342} *100[/tex] = -3.45618
You cannot have a negative percentage. Therefore the answer is 3.45618%
What’s the independent variable, dependent variable, experimental variable and constant?Scenario #1: Traci thinks that instrumental music played in the office will increase the productivity
of workers at the office. She creates two groups of 50 workers each and assigns each group the
same task in this case, they are asked to staple a set of papers). Group A has instrumental music
playing while they work. Group B does not have any music playing for them. After an hour, Traci
counts how many stacks of papers each group has made. Group A made 2,113 stacks. Group B
made 1,587 stacks.
Answer:
independent variable- instrumental music
dependent variable- Number of stacks of papers made
experimental variable- Group A has instrumental music
playing
constant- same task,
Explanation:
The most appropriate way to measure a volume of soda
Answer:
measure in cups or fluid ounces
Explanation:
Answer:
Liters
Explanation:
Trust me
When an iron nail is ground into powder, its mass ____.
a. stays the same
b. decreases
c. increases
d. cannot be determined
When paper turns yellow-brown upon exposure to sunlight, what type of change is likely taking place?
a. a physical change
b. a chemical change
c. neither a physical change nor a chemical change
d. both a physical change and a chemical change
Explanation:
(a) The mass of an object remains the same always. It is independent of its location. In this case, an iron nail is ground into powder. It means that its mass will remain unchanged. Hence, (a) is the correct option.
(b) Whenever there is a change of color of an object, a chemical reaction occurs. It shows that a reaction happens there. In this problem, a paper turns yellow-brown upon exposure to sunlight. A chemical reaction takes place there. Hence, (b) is the correct option.
1) The mass of any substance remains the same irrespective of the state.
Thus, an iron nail ground into powder should have the same mass unless parts of it got lost during grinding.
2) A paper that turns yellow-brown upon exposure to sunlight is likely undergoing a chemical change. It could be that the light oxidizes the atoms of the paper.
Chemical changes occur when the atoms of a substance combine with another substance to form new products. New products are not formed in physical changes and the original product can be retrieved by physical means.
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Which of these is a physical property?
A) ability to burn a piece pf paper
B) pure sodium reacts violently with water
C) the boiling point of water is 100°C
D) helium does not tend to react with anything
Answer:
the boiling point of water is 100°C
Explanation:
Which component of air is given off when silicon dioxide is passed through air during the industrial preparation of air
Answer:
Answer the following questions: What is the composition of air? Answer: Air is composed of nitrogen, oxygen, carbon dioxide, many other gases, water vapour and dust particles. Which gas in the atmosphere is essential for respiration?
Explanation:
Answer:
poop
Explanation:
cus poop
How many significant figures are in 0.0810300600 kg
Answer: 2.
Explanation:
Write the net ionic equation for the acid-base reaction of hydrochloric acid with phosphine. (Include states-of-matter under the given conditions in your answer.)
The net ionic equation for the acid-base reaction of hydrochloric acid with phosphine is PH3(aq) + H⁺(aq) → PH⁺₄ (aq)
What is a Chemical reaction?A chemical reaction shows us how substances interact which brings about changes in the composition of the reactants. Two types of Chemical reactions includes:
the net ionic equation balanced chemical equation.The net ionic equation of a chemical equation tells us only elements and ions directly involved in the chemical reaction.
Now for the reaction of hydrochloric acid, HCl with phosphine, PH3,
First write the aqueous substances in their ionic components
PH3(aq) + HCl(aq)→ PH4Cl(aq)
PH3(aq) + H⁺(aq) +Cl⁻(aq) → PH⁺₄ (aq) + Cl⁻(aq)
Then we remove the ions that do not take part in the reaction, Cl⁻(aq)
So we are left with
PH₃(aq) + H⁺(aq) → PH⁺₄ (aq)
Therefore, the net ionic equation for the reaction of hydrochloric acid with phosphine is PH₃(aq) + H⁺(aq) → PH⁺₄ (aq)
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I need help, pls someone help me!!
Round the the number below to the following places:
1254.6027
Rounded to the nearest... Correctly Rounded Number (Answer)
1000 place
100 place
10 place
1 place
10th place
100th place
1000th place
Answer: 1265.6037
Explanation:
What is the main cause of global convection currents?
Answer:
The main cause of global convection currents is the uneven heating of the earth by the sun. Hope this helped! :)
The main cause of global convection current is differential heating, that is the temperature difference in different levels of atmosphere.
What is convection current?Convection current is the heat transfer by fluid movement in the earth crust between different temperature regions. The density of fluids differs due to the temperature gradients and thus heated fluids raises and cooled fluid sinks.
The heated fluid movement causes the movement of plates of earth. The molten rock deep inside the earth crust circulates by the convection current.
Hence, the main cause of global convection current is the differential heating of the atmosphere.
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Round the number 3456.5 to two significant figures.
Explanation:
35- this is the answer in 2s.f
When rounding a number to two significant figures, we consider the first two most significant digits from the left. In this case, the number is 3456.5. 3456.5 rounded to two significant figures is 3500.
Rounding numbers is a common mathematical process used to simplify or approximate values to a desired level of precision. It involves adjusting a number to a specific decimal place or significant figure.
To round 3456.5 to two significant figures, we look at the first two digits: 34.
The next digit after the second significant digit is 5. Since 5 is greater than or equal to 5, we round up the last significant digit.
Therefore, rounding 3456.5 to two significant figures gives us:
3500
So, 3456.5 rounded to two significant figures is 3500.
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HELP ASAP!! A pebble is dropped into a graduated cylinder and the volume rises from 25.0 mL to 31.0 mL. The mass of the pebble is 2.9g. What is the density of the pebble? (g/mL)
Answer:
The density of the pebble is 0.483g/mL (rounded), but it's 0.48333333333333 without rounding. Hope this helped! :)
Explanation:
Volume= 6.0mL Density=Mass/Volume
Mass= 2.9g
D=2.9g/6.0mL
D=0.48333333333333g/mL
or
D≈0.483g/mL
Which statement describes a controlled experiment? A.) It has one group in which the controlled variable is tested, and another in which the manipulated variable is tested. B.) It has one group in which the responding variable is tested, and another in which the responding variable is not tested. C.) It has one group in which the manipulated variable is tested, and another in which the responding variable is tested. D.) It has one group in which the manipulated variable is tested, and another in which the manipulated variable is not tested.
Answer:C.) It has one group in which the manipulated variable is tested, and another in which the responding variable is tested
Explanation: hope this helps
The statement that describes a controlled experiment is that it has one group in which the manipulated variable is tested, and another in which the responding variable is tested (option C).
What is a controlled experiment?A controlled experiment is an experiment where one variable is tested at a time and all other variables are kept constant.
An experiment consists of a manipulated or independent variable, which is the variable changed, and a responding or dependent variable, which is the variable measured.
Therefore, statement that describes a controlled experiment is that it has one group in which the manipulated variable is tested, and another in which the responding variable is tested.
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Describe how the charges of the subatomic particles interact with one another.
Answer:
Electrons, Protons, and Neutrons. ... Protons are another type of subatomic particle found in atoms. They have a positive charge so they are attracted to negative objects and repelled from positive objects. Again, this means that protons repel each other
It is believed the major reason for the decline in amphibian species is _______.
a.
death through disease
b.
changing reproductive habits
c.
mutation
d.
climate change
Answer: It is believed the major reason for the decline in amphibian species is death through disease.
Explanation:
The major reason for the decline in amphibian species is climate change.
Amphibians are organisms that can live on land and in water. They are
usually found around moist areas because they need water bodies to cool
off in order for their survival.
Climate change is characterized by an increase in temperature which
doesn't favor them as they lose more water which thereby threatens survival
and leads to their decline in the ecosystem.
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Which of the following most likely explains why the chemical symbol for calcium is Ca?
A. The symbol C was already used for carbon.
B. The symbol was assigned by modern alchemists.
C. Calcium is made of more than one type of atom.
Answer:
it is a latin word, so B
Explanation:
You are stranded on survivor island in which there are already 375 other survivors. For every survivor there are two hands, for every hand there is an eye; for every eye, there is a footprint; and for every 4 footprints, there is a dinosaur; for every half dinosaur, there are40 ducks; for every 20 ducks, there are 32 pineapples; for every 12 pineapples, there is 1 palm tree; for every 30 palm trees, there is 1 wave; for every wave, there are 100 anchors; and for every anchor, there are 30 turtles. How many turtles are on the island? Use dimensional analysis to solve this calculation.
Answer:
its in the answer
Explanation:
The density of lead is 11.342 g/cm 3 . What would be the volume of a 200.0 g sample of this metal?
Answer:
The answer is
17.63 mLExplanation:
The volume of a substance when given the density and mass can be found by using the formula
[tex]volume = \frac{mass}{density} \\ [/tex]
From the question
mass of lead = 200 g
density = 11.342 g/cm³
It's volume is
[tex]volume = \frac{200}{11.342} \\ = 17.6335743...[/tex]
We have the final answer as
17.63 mLHope this helps you
A
is a changeable factor in an experiment.
O THEORY
O LAW
O HYPOTHESIS
O CONTROL
O VARIABLE
Answer:
Variable is a changebale factor in an experiment.
Explanation:
Answer: O VARIABLE
Explanation:
HELP PLS!!!!!!! NEED THIS IN 5 MINS
2. What kind of bond is pictured in the diagram to the left? Describe the movement of the valence electrons in the bond above? (Hint: Sharing or giving up?)
in a complete sentence pls
Answer:
Sharing or covalent bonding is taking place.
Explanation:
The valence electron will be shared by both the atoms so that means that the election will move around both of the atoms.
Silus wants to monitor the temperature of a reaction every 0.5 seconds for 30 minutes. He plans to generate a graph of the temperature values over time and insert the graph into a text document. Which pair of tools would be best for Silus to use?
Answer:
an electronic temperature probe and a computer
The total number of protons and neutrons in an atom is its ___________________.
Answer:
nuggets
Explanation:
tazte very good
Answer:
It's atomic number is 2 so it has 2 protons. It's nucleus also contains 2 neutronns so 2+2=4 the answer is 4 in total.
Explanation:
I think. hehe I hope this helps though.
Match the labels to the
diagram.
Cell
Vacuole
membrane
Nucleus
Endoplasmic
reticulum
Ribosomes
Lysosome
Golg!
Mitochondrion
body
Answer:
Explanation hope this help and i hope this is the right answer for the question
At the equator, the sun shine heats the air and
causes it to rise. At the north and south pole
there is less direct sun to warm the air, so this
air ______ (blank)
1. rinses
2. stinks
3. rises
4. sinks
A hypothesis is based on the analysis of data collected in a controlled
experiment.
True
False